A classical monopole antenna is a type of radio antenna that consists of a straight rod-shaped conductor that is typically mounted perpendicularly over some type of conductive surface, called a ground plane. In some cases, the ground plane is the earth's surface, while in other cases, the ground plane is formed of a conductive material. The classical monopole antenna has an omnidirectional radiation pattern meaning that it radiates equal power in all azimuthal directions perpendicular to the antenna resulting in a donut shaped radiation pattern. The height of monopole antennas is inversely related to the transmission frequency because operation at low frequencies results in a very large electromagnetic wavelength. As a result, a traditional monopole antenna operating at low frequencies is also physically very large. The physically large size makes the monopole antenna challenging to use in low-profile applications at low frequencies.